A Case of Cutaneous Anthrax in an Infant
Mary Wu Chang, MD, New York University School of Medicine, recounted her experiences diagnosing and caring for a 7-month-old infant in whom severe systemic symptoms developed secondary to cutaneous anthrax infection. The source of the infection was presumed to be contact with anthrax spores at his mother's workplace, the office of a television news organization.
Dr. Chang emphasized the difficulty in recognizing this infection early, because it initially appeared as a painless red macule on the arm that evolved into a papule with serous drainage. When the lesion progressed and the patient was unable to tolerate oral antibiotics, he was admitted to the hospital for intravenous therapy. The lesion was incised and drained, with a presumptive diagnosis of abscess. When massive edema developed, the differential diagnosis was expanded to include osteomyelitis, arachnid bite, and obstructive mass lesion.
Subsequently, the more classic findings of central necrosis with surrounding local edema developed. Dr. Chang's patient was unique because severe systemic symptoms developed, including hemolytic anemia, coagulopathy, hyponatremia, and renal insufficiency. On day 12 of the patient's hospitalization, the first case of cutaneous anthrax in an adult was reported in New York City, and Dr. Chang's patient was evaluated for cutaneous anthrax, even though he had almost fully recovered by that time. He subsequently received oral ciprofloxacin followed by amoxicillin, and by day 60 the lesion had healed with little evidence of scarring.
Anthrax is a gram-positive rod that appears jointed and bamboo-shaped in culture. Naturally occurring anthrax occurs in those who handle infected herbivorous animals or their hides ("wool-sorters' disease"), with cutaneous disease accounting for more than 95% of cases. Disease occurs when anthrax spores found in the environment germinate after entry into the skin, lungs, or gastrointestinal tract. The resulting bacteria subsequently elaborate at least 3 toxins, which are responsible for the clinical signs and symptoms. The classic cutaneous findings include a painless papule that then becomes vesicular or edematous with central necrosis. The differential diagnosis includes orf, spider bite, and rickettsial pox.
When untreated, cutaneous anthrax can resolve spontaneously in some cases; however, systemic complications may develop that can lead to mortality in 20% of cases. Antibiotic therapy decreases mortality to less than 1%. Inhalational anthrax is much more likely to cause significant systemic disease and is associated with high mortality even with antibiotic therapy.
The local health department should be notified in suspicious cases. A suspicious lesion should be swabbed for culture -- either the vesicle itself, exudates, or the edge under an eschar are appropriate sampling sites -- and the laboratory must be aware of your suspicions. Biopsy, serum polymerase chain reaction, and blood cultures are also appropriate investigations; biopsy may not be diagnostic but is useful to rule out other processes. Treatment consists of ciprofloxacin or doxycycline. Intravenous therapy is required if systemic symptoms are present or the patient is younger than 2 years old.
Medscape Dermatology. 2002;3(2) © 2002 Medscape
Cite this: Two Colleagues, Two Perspectives: Report From the Society for Pediatric Dermatology Annual Meeting, Part 1 - Medscape - Oct 01, 2002.